Air-preheating mechanism for mill-furnaces



w. w. LESTfR. AIR PREHEATING MECHANISM FOR MILL FURNACES.

APPLICATION FILED MAY 8, 1920.

Patehfned Aug. 30,1921.

PATENT OFFICE.

WILLIAM W. LESTER, OI CINCINNATI, ,OH'IO.

Amrmm'rme MECHANISM FOR MILL-FURNACES.

Specification of Letters Patent.

Patented Aug. 30, 1921.

Application filed Kay 8, 1920. Serial No. 879,736.

To all whom it may concern Be it known that I, WILLIAM W. Learns, a citizen of the United States ofAmerica and resident of Cincinnati, in the county of Hamilton and State of Ohio, have invented a new and useful Improvement in Air-Preheating Mechanism for Mill-Furnaces, of which the following is a specification.

An object of my invention is to eliminate the cold air draft and to provide a heated draft for furnaces used in plate mills, rolling mills, sheet mills and other similar mills.

Another object of my invention is to eliminate to a great extent the difference n degree between the top and bottom heats 1n the furnaces used in such mills.

Another object is to provide a devlce whereby the air draft used in such furnaces can be pre-heated by the exhaust gases.

These and other objects are attained by means described herein and disclosed in the accompanying drawing in which:

Figure 1 is a view taken on line 1 1 of Fig. 2 and showing a device embod mg my invention, part in rear elevation an part in section.

Fig. 2 is a view on line 2-2 of Fig. 1,

1 part in plan and part in section.

My invention comprises an air pre-heating device A mounted upon, or so spaced in re 8.

tion to, a furnace B, of the type referred to, that the gases escaping from such furnace will heat the intake air of the forced draft as it passes through the device A, to the smoke-stack C.

The oven or pre-heating device A is preferably of a type similar to the muffle heater, and comprises a series of horizontal forced air draft ducts a arranged in horizontal and vertical alinement, and a series of horizontal gas ducts 0: arranged in horizontal and vertical alinement and at right angles to the forced air ducts. The horizontal series of draft and gas ducts are alternately interposed between one'another. The baflles a, a, a, a a, a", a, a, a, and a", are so arranged that the air draft and the gases passing through the device A must both follow circuitous passages throu h the ducts befor the reach the conduit and the smokestack Thefurnace B may be of any type, but for example I show a furnace of a reverberatory type, such as used in some mills of the type enumerated.

The operation of my device is as follows:

The hot gases in the furnace, pass from the furnace fires to the chamber B where the material to be worked upon is heated; then the pass from the chamber B, through t e flue c, and through the series of gas ducts a in the heater A, following the path shown by the single headed arrows, until they reach the smoke-stack C. The air draft takes the course marked by the double headed arrows, assing from the fan D through the duct B to and through the air draft. ducts a in the heater and throu h the conduit A, directing such preheate draft to the furnace fires. This preheated air is fed to the furnace in the same manner employed in mills of this type in feeding cold air draft to the furnaces, except that the conduit A must be extended up to the place where the hot air draft is to be released upon the furnace fires. The heater A and conduit A are constructed, preferably of fire brick, because of the intense heat to which they are subjected.

Because only pre-heated air is fed to the furnace, the cold air drafts that in the cold draft furnace pass by the burning fuel and are the cause of the great difference in degree of the top and bottom heats in the furnace, are eliminated, thereby assuring greater uniformity between the top and bottom heats in the chamber B. The benefits derived from such a condition are that the material to be worked upon is more evenly heated, the furnace does not require as much fuel nor is it necessary to provide as intense a fire within the furnace because there are no effects of any cold air draft to be overcome. The evenness of heat within the chamber B eliminates drip from the top of the furnace, avoids oxidizing of the material thereby giving a softer metal to be," worked upon, and numerous other desir able features.

What I claim is:

1. The combination with a metal heating furnace, of means adapted to create a forced air draft, means adapted to subject th. forced air draft to the heat of the exhaust gases, and means to convey the forced air draft, after it is heated, 'to the furnace fires.

2. The combination with a metal heating furnace, of an oven, means adapted to create a forced air draft and to force such draft through the oven means to carry the exhaust gases through the oven on their way to the smoke-stack, and means to convey the forced air draft from the oven to the furnace fires.

3. The combination with a metal heatin furnace, of an oven comprising a series 0 horizontal ducts invertical and horizontal alinement, a second series of horizontal ducts in vertical and horizontal alinement, the two series of ducts bein laced substantially at right angles an li eing alternately interposed in, horizontal layers, baffie plates adapted to form with the ducts, two independent circuitous passages through the oven, means adapted to force an air draft through one circuitous assa e in the oven, means to conve such raft tom the oven to the furnace res, means ada ted to convey the exhaust gases from the urnace to the second circuitous passage in the oven, and means to convey the exhaust gases from the oven to the smoke-stack.

In witness whereof I have hereunto subscribed my name this 1st da of Ma 1920.

WILLIAM w.

LES ER.

DISCLAIMER 1,389,059Q-William W. Lester, Cincinnati, Ohio. AIB-PREHEATING Ml-zcmmlsu FOR MILL-FURNACES. Patent dated August 30, 1921. Disclaimer filed March 30, 1934, by the pabentee. Hereb enters his disclaimer to that part of the claim in said specification which relates to urnwces other than sheet mill furnaces, to wit:

He hereby disclaims from the scbpe of claims 1, 2, and 3, all metal heating furnaces except sheet mill furnaces.

Qfiic'ial Gazeite April 24, 1.984.] 

